23523.The coercivity of a small magnet where the ferromagnet gets demagnetized is 3 × 103 A m–1. The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside the solenoid, is :
60 mA
3 A
6 A
30 mA
23524.Hysteresis loops for two magnetic materials A and B are given below:
These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use:
These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use:
A for electromagnets and B for electric generators
A for transformers and B for electric generators
B for electromagnets and transformers
A for electric generators and transformers
23525.The magnetic lines of force inside a bar magnet
are from north–pole to south–pole of the magnet.
do not exist.
depend upon the area of cross–section of the bar magnet.
are from south–pole to north–pole of the magnet.
23526.An iron rod is placed parallel to magnetic field of intensity 2000 A/m. The magnetic flux through the rod is 6 × 10–4 Wb and its cross–sectional area is 3 cm2. The magnetic permeability of the rod in Wb/A–m is
10–1
10–2
10–3
10–4
23527.The magnetic susceptibility is negative for
Ferromagnetic material only
Paramagnetic and ferromagnetic materials
Diamagnetic material only
Paramagnetic material only